I did not know of that Exposition. I read that the brownie and other hugely iconic American foodstuffs were introduced then as well. A defining moment in terms of identity, seen from today.

As for the rest, indeed. My comment was more about the short term national mood of these few days or weeks. The larger trends will continue unabated, catabolic stairstep collapse, etc.
I had not reflected yet about the last point you make, which is the temptation of a Reaganic Morning in America 2.0. It would seem likely and at the same time the world has changed a lot in 5 years, and keeps doing it fast, now. Here's hoping this respite will be put to good use.